1. The Field of the Invention
The invention is in the field of petroleum recovery, more particularly in the field of assessing recoverable petroleum reservoir reserves and potential for increasing the amount of recoverable petroleum from a reservoir.
2. The Relevant Technology
Petroleum is a critical fuel source and is the life blood of modern society. There is tremendous economic opportunity in finding and extracting petroleum. Due to a variety of technical and geological obstacles, it is typically impossible to recover all of the petroleum contained in a reservoir.
Until 1965, typical petroleum reservoir recovery rates were approximately 25%. That is, that was the fraction of petroleum within a reservoir that could be economically and/or feasibly extracted. The remaining 75% was essentially unrecoverable due to technological and/or economic impediments. Since then, with advancing technologies and increasing economic incentives due to higher crude oil prices, the average recovery rate has increased to about 35%. Further increases may be possible through improved recovery techniques and management and higher economic incentives. The challenge is to reliably assess the potential for reserves increases in order to accurately determine the present value and production capacity of a reservoir.
Given the high cost of exploration, dwindling opportunities to find new petroleum reservoirs, and the rising cost of petroleum as a commodity, there currently exists a tremendous economic opportunity for more accurately assessing petroleum reserves and the potential for reserves increases. Current methods for assessing petroleum reserves and potential reserves increases take years, and there is no method of standard validation for the results. Moreover, because production and reservoir depletion continue during the assessment process, the results may in fact comprise obsolete data and assumptions. There is currently no known method for accurately assessing petroleum reservoir reserves and the potential for increasing reserves in a short period of time (i.e., within days, weeks or months rather than years).
While the technology may, in fact, exist to increase total long-term recovery for a petroleum reservoir, an impediment to implementing an intelligent long-term plan for maximizing current output, extending the life of a given reservoir, and increasing total recovery is the inability to accurately assess the health and deficiencies of the reservoir. For example, some or all of the producing wells of a reservoir may show diminishing output, which might lead some to believe the reservoir is drying up. However, the reservoir may, in fact, contain much larger quantities of recoverable petroleum but be under-producing simply due to poor placement and/or management of the existing wells and the failure to know whether and where to place new wells. The inability to properly diagnose inefficiencies and failures and implement an intelligent recovery plan can result in diminished short-term productivity and long-term recovery of petroleum from a reservoir.
In general, those who operate production facilities typically focus on oil well maintenance and may even implement the latest technologies for maximizing well output. They fail, however, to understand the total picture of health and longevity of the reservoir, which may be serviced by several wells. Wells are difficult and expensive to drill and operate. Once a given number of wells are in place, it may be economically infeasible to drill more wells in order to increase reservoir production (i.e., the marginal cost may exceed the marginal benefit). Moreover, there may be no apparent reason to shut down a producing well even though doing so might actually increase long-term recovery. The knowledge of when and why to shut down or alter a producing well and/or properly construct a new well often eludes even the most experienced producers and well managers. The failure to properly manage existing wells and/or place and construct new wells can increase capital costs while reducing ultimate recovery.
The main impediment to maximizing production and recovery from a reservoir is the inability to gather, intelligently analyze, and correctly understand the relevant data. Diagnosing the health of a petroleum reservoir is not straightforward and is much like trying to decipher the health of a human body, but at a location far beneath the earth or ocean. Moreover, the available data may take years to accumulate and assess, yet may be dynamically changing, making it difficult, if not impossible, to formulate and implement an economically and/or technically feasible plan of action. The result is continuing low productivity and long-term recovery from the petroleum reservoir.